Field of the Disclosure
The present disclosure relates to a display device, and more particularly, to a display device capable of suppressing external light reflection when light is incident from tilted directions from a viewing angle, thereby improving contrast and visibility.
Description of the Background
In recent years, flat panel display devices which can be easily realized with a large area and can be made thin and light have been rapidly appeared in the market.
Such a display device includes a liquid crystal display (LCD), a plasma display panel (PDP), an organic light emitting display (OLED), and the like.
These flat panel display devices use a circular polarizer or an anti-reflective (AR) film or the like in order to suppress reflection of external light and improve contrast and visibility.
FIG. 1 is a cross-sectional view schematically illustrating a display device according to the related art.
Referring to FIG. 1, a display device of the related art includes a display device 10, an anti-reflection polarizing film 20 disposed on the display device 10, and a cover window 30 disposed on the anti-reflection polarizing film 20.
Here, the anti-reflection polarizing film 20 is a component for preventing incident light from being reflected in a predetermined direction such as a linear polarizer (refer to reference numeral 20a in FIG. 2) and a circular polarizer (refer to reference numeral 20b in FIG. 2).
FIG. 2 is a view schematically illustrating a light path of front incident light in a display device according to the related art.
Referring to FIG. 2, light incident on the front surface is linearly polarized at 0 degree while passing through the linear polarizer 20a, and the 0-degree linearly polarized light is converted into left-handed circularly polarized light while passing through the circular polarizer 20b therebelow.
Then, the left-handed circularly polarized light is reflected from the display panel 10 and converted into right-handed circularly polarized light.
Furthermore, the converted right-handed circularly polarized light is converted into 90-degree linearly polarized light while passing through the circular polarizer 20b, and the 90-degree linearly polarized light is finally absorbed through the linear polarizer 20a to prevent reflection.
Therefore, even if a part of light incident on the front surface is reflected within the display device, the reflected light is substantially absorbed into an inside of the display device, namely, the linear polarizer 20a, to prevent reflection to an outside of the display device.
FIG. 3 is a view schematically illustrating a light path of side incident light in a display device according to the related art.
However, referring to FIG. 3, light incident on a side having a viewing angle of less than 90 degrees is unable to realize complete linear and circular polarization while passing through the linear polarizer 20a and the circular polarizer 20b, and a part of light is converted into elliptically polarized light, and finally passes through the linear polarizer 20a to reflect the light to the outside.
Therefore, in a display device according to the related art, in case of light incident vertically on the front surface, reflection to the outside of the display device may be prevented, but when the light incident from tilted directions from a viewing angle of the display device, reflection to the outside of the display device may increase, thereby resulting in that the reflectance is high and a color change such as a color shift is present.